1. Field of the Invention
This invention relates generally to fabricating annular polymeric articles, and more particularly to a method of making annular polymeric articles and moulds for carrying out the method.
2. Description of the Prior Art
Known in the art are methods of making annular polymeric articles in which a workpiece is placed on a shaping cylindrical surface, after which the workpiece is squeezed on this surface and vulcanized. Squeezing is done by sector elements arranged around the cylindrical shaping surface by moving the sectors radially.
There are also known moulds for making annular polymeric articles comprising a cylindrical core (cylindrical shaping surface) serving to accommodate thereon elements of the article. Arranged around the cylindrical core are sectors for squeezing the workpiece kinematically linked with a drive for moving these sectors radially to form a closed circuit. For avoiding unproductive losses the outer sides of the sectors at their abutments are provided with recesses accommodating locks to prevent leaks of elastic material (SU, A, 195,088).
The aforedescribed devices can be used, however, only for making one-sided toothed belts, because in the course of moulding the elastic material is at first forced to the clearance between the sectors to gradually flow then to the molding interior as the clearance diminishes accompanied by the formation of fins in the zone of abutment. When making polymeric articles having a wear-resistant fabric lining at the outer surface, such as double-sided toothed belts, the fabric lining between the sectors is subject to biting or cutting. Due to the flow of the elastic material to the clearance between the sectors and then due to the backflow of the elastic material to the molding zone insufficient moulding takes place in the abutment zone, especially during fabrication of shaped articles.